A new study from the CDC has found that the rate of twins has dramatically increased over the past three decades. Compared to 1980, the twin rate increased by 76% by 2009. While in 1980, 1 in 53 babies born were a twin, in 2009, 1 in every 30 babies born is a twin.
The reason seems to be caused by the use of fertility drugs, which boost your chances for multiples, and more women having children after age 35. Having a baby later in life increases your odds for twins. The CDC study found that the twin rate grew nearly 100% for women ages 35 and 39, and more than 200% for women age 40 and over.
An MSNBC.com article spoke about the increased rates of twinning, and their expert commented that the reason for more twinning after 35 may be due to older eggs, saying that older eggs may divide in abnormal ways.
This implied that the increase in twins for women over 35 is for monozygotic twins, or identical twins. In fact, that's inaccurate. The increased risk for twins over 35 is for dizygotic twins - non-identical twins. With monozygotic twins, one eggs splits, but with dizygotic twins, two different eggs are released and fertilized. (Learn more about the differences between monozygotic and dizygotic twins.)
Unless there's a study I'm not aware of, age is not connected to identical twin rates.
I wondered why the expert didn't explain that FSH, a hormone that plays an essential role in the ovulation, increases as a woman ages. FSH is the hormone that you inject with gonadotropin fertility treatments. While FSH increases because the eggs become less responsive as a woman ages, it does make some sense that there will be months when the eggs in the queue are eager to ovulate and more than one egg may get released.
It also just makes sense from a biological stand point. Fertility is going down, and the chances for any baby are decreasing. So the body makes a last ditch effort and starts releasing extras.
Did you conceive twins while taking fertility drugs? (I did! They're playing downstairs as I type, in fact!) Are you hopeful or worried about conceiving twins during treatment? Do you think the increased rate of twinning is a good, bad thing, or neither? Please feel free to share in the comments below.
Learn more about twins:
- Quiz: Are My Odds for Twins Higher Than Most?
- What Increase Your Odds for Twins
- Pregnancy Signs and Symptoms for Twins
- Quiz: Could I Be Pregnant with Twins?
- What Are Your Chances for Clomid Twins?
- Should I Get Pregnant with Twins on Purpose?
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